Experimental study on the effect of extracting low-molecular-weight compounds with organic solvents on coal spontaneous combustion
FANG Zhenzhu
ZHU Jianwen
ZHANG Jie
LI Jiangjiang
CUI Chuanbo
Abstract：In order to study the effect of low molecular compounds in coal on the spontaneous combustion of coal,this study utilizes the technique of organic solvent extraction of low molecular compounds in coal to analyze the effect of low molecular compounds on the spontaneous combustion of coal.The results show that the extraction method does not affect the trend of the extraction rate of the three solvents,which were DMF>THF>JC.The extraction rate of ultrasonic assisted extraction was greater than that of Soxhlet ex-traction.The ultrasonic-assisted extraction rates of JC,THF,and DMF were respectively 33.77%,112.15%,and 87.85%higher than those of the Soxhlet extraction.The effect of ultrasonic extraction on functional groups was greater than that of Soxhlet extraction.The functional group area increased by 22.74%,25.05%,and 15.26%after JC,DMF,and THF Soxhlet extraction,and increased by 28.85%,33.71%,and 21.31%after ultrasonic extraction.After the extraction of raw coal by methanol,the content of functional groups in the remaining coal changed with a small magnitude;after the extraction of THF,the content of-OH decreased,and the percentage of other oxygen-containing functional groups increased;after the extraction of DMF,the content of aliphatic hydrocar-bons in the coal samples decreased dramatically,the content of-OH and-COOH decreased slightly,and the content of C=O and C-O content increased substantially.The complexity of the pores increased after extraction of low molecular chemosynthesis.The maximum pore volume of JC,THF,and DMF reached 0.053 cm3/g,0.060 cm3/g,and 0.040 cm3/g after Soxhlet extraction,and the percentage of mesopores was expanded from 75%before to 83%,77.5%,and 83.3%,and the percentage of macropores was de-creased from 25%of the original coal to 17.0%,22.5%,and 16.7%.After ultrasonic extraction,the total pore volume increased by 0.129 cm3/g,0.120 cm3/g,0.120 cm3/g,compared with the Soxhlet extraction.The energy generated by ultrasound enables the solvent to better penetrate into the coal molecules,resulting in better ultrasonic extraction than Soxhlet extraction.The oxygen con-sumption capacity of the extracted coal was positively correlated with the magnitude of the extraction rate.For the same solvent,the oxygen consumption of ultrasonically treated coal samples was higher than that of Soxhlet-extracted coal samples because the in-crease in pore size and specific surface gave more active sites for the residual coal to facilitate oxidation reactions.The increasing trend of CO gas volume fraction and oxygen consumption capacity of the extracted coal were DMF>THF>JC,which indicated that the small molecular structure of coal had an inhibitory effect on the spontaneous combustion of coal.
Keywords：organic solventextraction technologylow-molecular-weight compoundsSoxhlet extractionmicrostructurespontan-eous combustion of coalultrasonic-assisted extraction
Publication Date：2026-02-20
Online Publishing Date：2026-03-19(First online date of this platform, not the publication date of the document)
Pages：9( 124-132 )